Ah half marathon training! It seems like it can only be good for you and your body. You’re torching calories, toning up those legs, and all that exercise should totally help control my blood sugars, right?

Um. Not really. At least, not right now while I’m getting used to running longer distances again. It’s been two years since my last half marathon, and although I’ve done a variety of sports and events since then (plus one three-month seemingly endless walk around Southeast Asia) I have not run longer than about 45 minutes in a veeeery long time. So on Saturday, I was in for a rude awakening in the BG department after I clocked a five mile training run.

I started off at a respectable 95 mg/dL, and cranked my basals down by 50%. I held steady for while, but just past the halfway point, the arrow on my CGM started to slant downwards, and every five minutes I was dropping lower. When I hit 75mg/dL, I decided to crack open a GU pack now rather than later to avoid a steeper low. Plus, I dropped my basals by 80%. I think I was dropping faster than I thought though, because another five minutes past and I was feeling pretty light-headed and tired (not that running can’t do that to you on it’s own, because it does, but you all know what I mean!). Knowing I’d just taken down 18 grams of CHO though, I felt comfortable pressing on, and I was back in the 80s and rising by the time I turned on my block. I felt safe again and satisfied that I’d still made it through the run despite the low.

That is, under the 80 turned into 180mg/dL, and then 230, and finally peaked at 275mg/dL by the time I was done with lunch. Ick. I have to blame my liver partially, since I did the training run on an empty stomach, and also the GU pack with a few more grams of CHO than was probably needed. And I had turned my basals down more than required I think. To top it all off, I didn’t bolus early enough for my lunch and that contributed to the meteoric rise. I rage bolused the stubborn high back down, and, as rage boluses tend to do, they all caught up with each other around 4pm when I crashed hard to a low under 45mg/dL. Not only had I corrected too much, but I was more sensitive to the insulin because of my long run that morning, which I had not taken in to account as I corrected the high.

In my sweaty, low fog, I reminded myself that with training for a distance event, subtle changes can have a huge effect. The goal here is to tweak things ever so slightly in one direction, not all at once with one giant swoop. It’s like going to power steering after having a regular wheel – you don’t need a ton of force to change the course of your BGs when you’re dealing with a ton of exercise. Small amounts of carb and insulin can make all the difference, while large amounts of either can inversely create massive problems.

As I head in to the next few weeks of training, I’ll need to work on some precision management of my numbers as I build mileage. The good news is, I have the tools to do it – pump, CGM, quick acting carbs, and the bat belt to carry it all in. Such a good look, right? Ha.

Comments

I wish I had the magic bullet piece of advice that would make distance running free from complications… but all I can say is “I’ve been there!” Like, twice a year! It is a fine balancing act. One thing that has helped me to is to keep a written record of what I’ve done for each of my long runs – what % I lowered my basal, what I ate, anything I bolused, and what the result was. And, boring as it is, to keep my breakfast and fuel just about always the same, and to always try to run at the same time. Someone needs to develop a second medal that T1Ds earn at the finish line, for all the math involved in making it there.

Jennifer that’s great advice to keep a diary! I should do that, even if it’s just for the mornings I go on a long run to try and make a little sense out of it. THank you for that. And I agree – we need special medals for all the MATH!!!!

Maybe this will help but it is what sorta(like anything D is the same every time) mostly works.

I found that I temp basal for the peak of the insulin, so 90-120min before I leave. This will be the value that doesn’t drop me low during the run. Usually it starts, if I have too much insulin, around 50min. If I run without a temp basal starting at about 20min in I will start dropping very quickly. I will correct high BG’s sometimes and go from 25mmol/L to 5mmol/L in 30min of running. Suffice to say, pumping allows me to do anything exercise related.

The temp basal amount will take practice and logging. So try to get a bit of a routine and not go more than a day without a workout. This way you can keep your daytime sugars mostly normal. Heck, I have my basal/bolus rates set for me running as the norm and give extra insulin when I go more than a few days without running. I have also noticed that time of day/fasting makes a difference. Late afternoon and evenings require less insulin than a fasted morning. I have two approaches for this in the morning. I get up 4.5hrs prior and eat/bolus or I take more insulin. On race days I will definitely set the alarm and eat.

After the run was interesting before I got a CGM. I would go from about 5-6mmol/L to 25mmol/L in under an hour. And eating carb was out of the question. The CGM allowed me to be very aggressive and I now bolus about 2hrs worth of normal basal about 15min before I finish to get the active insulin up. Also, I set my temp basal fairly high at 200% for 90-120min. I started very subtle on this as it risks lows. But I can eat right after now and keep my sugar in range. It also can be different depending on the duration of the event. In my recent 50k race I cut that in half and I was in the zone afterwards.

The post run high BG can be a few things, you have low insulin levels. Your muscles have stopped gulping the glucose out of your blood stream. And your liver is still pumping out glucose because of the workout and low insulin levels. This is different in everyone, but if you are going high after a small bolus just before you finish might help a lot. Just test test test and learn the patterns.

One other thing I have noticed is that I find it is easiest to not bolus within about 4hrs of exercise if I can. This eliminates a variable that can be significant. The tail end of the IoB can do way more work when you start exercising and may be significant.

I have been running about 4 days a week anywhere from 4-7 miles at a time for over 6 months. I have always eaten breakfast around 8am, bolused low for it and then removed my pump completely for the run at 9am. I also have a Dexcom and typically go low during the run. I started taking GU a month ago and that has helped. I typically have to take it early on in the run, unless I’m trending up and above 180 and then I wait until my BG’s are trending down around 130. Thank goodness for GU! I do usually end up high 30 minutes after a run though and I think it is because I completely remove my pump? Argh!!! So frustrating. There is nothing worse than going low on a run. What do you use to carry all of your stuff?

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